Critically-ill patients who are admitted to intensive care units are thought to gain an added survival benefit from management by critical care physicians, but evidence of this benefit comes from small studies. A retrospective analysis of a large, prospectively-collected database of critically-ill patients was conducted to examine the association between mortality in critically ill patients and management by critical care physicians. We used data from Cerner Project Impact, a database of patients admitted to 123 Intensive Care Units (ICUs) in US hospitals, to compare hospital mortality of patients cared for entirely by critical care physicians (CCM) and patients cared for entirely by non-critical care physicians (non-CCM). To adjust for severity of illness, a modified Simplified Acute Physiology Score (SAPS II) was used. Since more severely-ill patients might be selectively referred to critical care physicians, a propensity score for critical care management was applied. Patients were grouped into six categories, defined by patient management type (CCM vs. no CCM) and ICU type (95% of patients received CCM, 5-95% CCM, or 5% CCM). Logistic regressions were performed, using hospital death as the dependent variable. We found that among 101,832 patients, those receiving CCM were generally sicker, received more procedures, and had higher mortality rates. After adjustment for severity of illness and propensity score, mortality rate remained higher for CCM patients than non-CCM patients. The difference in adjusted mortality was less for patients who were sicker and were predicted by propensity score to receive CCM. Study limitations are that there may be significant residual confounders for severity that remain unrecognized, even after controlling for expanded SAPS II and propensity score. In addition, ICUs in which there was no management by ICU physicians may also be a self-selected group of high performing ICUs. We conclude that in a large sample of ICU patients in the US, management by critical care physicians was not associated with a survival benefit. To the contrary, after controlling for severity of illness and propensity for receiving critical care management, the odds of mortality were significantly higher for patients managed by critical care physicians than those who were not. Although these results may be explained by unrecognized confounding by illness severity, further studies are needed to evaluate the effect of management by critical care physicians on outcomes in critically ill patients.